Download Effects of Alcohol Restriction on Ambulatory Blood Pressure, Heart

AJH
2002; 15:125–129
Effects of Alcohol Restriction on
Ambulatory Blood Pressure, Heart Rate,
and Heart Rate Variability in Japanese Men
Junichi Minami, Masayoshi Yoshii, Masakatsu Todoroki, Toshio Nishikimi,
Toshihiko Ishimitsu, Tatsushige Fukunaga, and Hiroaki Matsuoka
We investigated the effects of alcohol restriction on ambulatory blood pressure (BP), heart rate, and heart rate
variability in 33 Japanese male volunteers (37 ⫾ 1 years,
mean ⫾ SE), who were all habitual drinkers. Subjects
were told either to keep their usual drinking habits for 3
weeks (usual alcohol period), or to reduce alcohol intake
by at least half of their usual drinking amount (reduced
alcohol period). The ambulatory BP, heart rate, and electrocardiographic R-R intervals were measured during a
24-h period with a portable recorder on the last day of each
period. A power spectral analysis of R-R intervals was
performed to obtain the low-frequency (LF) and highfrequency (HF) components. The percentage of differences between adjacent normal R-R intervals ⬎50 msec
(pNN50) was also calculated. The amount of ethanol intake was significantly reduced from 70 ⫾ 5 mL/day in the
usual alcohol period to 19 ⫾ 3 mL/day in the reduced
alcohol period (P ⬍ .0001). The daytime systolic BP was
T
he relationship between high alcohol intake (typically three or more drinks per day) and elevated
blood pressure (BP) has been reported in a large
number of observational studies.1,2 A few trials have also
demonstrated that reductions in alcohol intake among
heavy drinkers can lower BP in normotensive and hypertensive men.3,4 On the basis of these findings, principal
guidelines on the treatment of hypertension support a
recommendation to limit alcohol intake to no more than
two drinks per day (men) and one drink per day (women)
among those who drink.5,6
So far, several studies have documented an association
between reduced heart rate variability and risk for cardiac
events.7,8 Although a few investigators have reported that
acute alcohol intake influenced heart rate variability in
healthy subjects9,10 and patients with cardiovascular disReceived June 22, 2001. Accepted September 13, 2001.
From the Department of Hypertension and Cardiorenal Medicine
(JM, MY, MT, TN, TI, HM), Dokkyo University School of Medicine,
Mibu, Tochigi; and Department of Forensic Medicine and Sciences (TF),
© 2002 by the American Journal of Hypertension, Ltd.
Published by Elsevier Science Inc.
significantly lower in the reduced alcohol period than in
the usual alcohol period by 4 ⫾ 1 mm Hg (P ⬍ .05). The
daytime and nighttime heart rate was significantly lower in
the reduced alcohol period than in the usual alcohol (P ⬍
.001 for each). The pNN50 and the HF component were
significantly higher in the reduced alcohol period than in
the usual alcohol period (P ⬍ .0001 for each). The LF/HF
ratio was significantly lower in the reduced period than
in the usual period (P ⬍ .01). These results demonstrate
that 3-week alcohol restriction produced reductions in
ambulatory systolic BP, heart rate, and the index of sympathovagal balance, and augmentations of parasympathetic indices of heart rate variability in Japanese male
drinkers. Am J Hypertens 2002;15:125–129 © 2002
American Journal of Hypertension, Ltd.
Key Words: Alcohol restriction, ambulatory blood
pressure, heart rate, heart rate variability, hypertension.
eases,11,12 little is known about the chronic effect of alcohol restriction on heart rate variability in habitual drinkers.
In this study, we investigated the effects of 3-week alcohol
restriction on ambulatory BP, heart rate, and time- and
frequency-domain measures of heart rate variability in
Japanese men who were habitual drinkers.
Methods
A total of 33 Japanese male volunteers were included in
the present study. The mean age (⫾ SE) was 36.9 ⫾ 1.1
years and the mean body mass index was 25.0 ⫾ 0.5
kg/m2. Information about drinking habits was obtained
using a questionnaire, with an inclusion criterion of ⱖ30
mL/day ethanol consumption. Beer was the most common
alcoholic beverage consumed, followed by sake. Other
Mie University School of Medicine, Mie, Japan.
Address correspondence and reprint requests to Dr. Junichi Minami,
Department of Hypertension and Cardiorenal Medicine, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan; e-mail:
[email protected]
0895-7061/02/$22.00
PII S0895-7061(01)02265-8
126
ALCOHOL AND BLOOD PRESSURE AND HEART RATE VARIABILITY
alcohol consumed included wine, whiskey, and other spirits. All of the subjects consumed alcohol in the evening,
and none drank in the morning or afternoon. No subjects
were receiving pharmacologic therapy. All subjects agreed
to participate after receiving a detailed explanation of the
nature and purpose of the study, and all subjects gave
written informed consent. The study protocol was in accordance with the Declaration of Helsinki (Somerset West
version, 1996) of the World Medical Association and was
approved by the Institutional Review Board of our institute. Using a randomized crossover design, subjects were
instructed to either maintain their usual drinking habits for
3 weeks, or to reduce alcohol intake by at least half of their
usual drinking amount. Seventeen subjects were assigned
first to the usual alcohol period and the other 16 subjects
were assigned to the reduced alcohol period. Daily alcohol
consumption was recorded by each subject throughout the
study. Venous blood samples were obtained on the last day
of each period. Serum ␥-glutamyl transpeptidase (GTP)
was determined with an autoanalyzer, Hitachi 7170 (Hitachi Ltd. Instruments, Tokyo, Japan).
The ambulatory BP was monitored every 30 min by a
cuff oscillometric device, TM-2425 (A&D Co., Tokyo,
Japan)13 on the last day of each period. The subjects were
asked to carry the device for 26 h, and the first 2 h of
recordings made at or near the hospital were omitted from
the later analysis. The ambulatory monitoring was performed during an average working day. The daytime and
the nighttime BP were calculated according to the true
waking and sleeping times of the individual subjects. The
same recorder was used for each subject for the entire
protocol to avoid different BP readings obtained by different recorders. The ambulatory BP recorder used in this
study also monitored the R-R interval of the electrocardiogram. The procedures of the power spectral analysis of
R-R intervals in this device were previously reported in
detail.14,15 Spectral R-R variability was computed as the
LF component (0.05 to 0.15 Hz) and HF component (0.15
to 0.40 Hz) using the autoregressive model from every
5-min block during a 24-h period. The LF/HF ratio was
calculated as an index of sympathovagal balance.16 We
also calculated the time-domain index, pNN50, which is
the percentage of differences between adjacent normal
R-R intervals ⬎50 msec. The pNN50 is a useful marker of
parasympathetic nerve activity.7 Heart rate was calculated
on the basis of continuous electrocardiographic recordings.
Values are expressed as means ⫾ SE. Comparisons
between the usual alcohol and reduced alcohol periods
were made using Student paired t test or one-way repeated
measures ANOVA as appropriate. Newman-Keul’s tests
were used as determined by the ANOVA results. For the
comparisons of power spectral data, the naturally logarithmic values, ln (the LF component), ln (the HF component), or ln (the LF/HF ratio), were used to normalize the
skewness of the data. Significance was determined as P ⬍
.05.
AJH–February 2002–VOL. 15, NO. 2, PART 1
FIG. 1. The 24-h trendgram of blood pressure (BP) and heart rate
during the usual alcohol (●) and reduced alcohol (䡩) periods. The
daytime systolic BP was significantly lower in the reduced alcohol
period than in the usual alcohol period, whereas the nighttime diastolic BP was insignificantly higher in the reduced alcohol period
than in the usual period. The daytime and nighttime heart rate
values were significantly lower in the reduced alcohol period than in
the usual alcohol period.
Results
All subjects completed the study protocol. The amount of
ethanol intake was significantly reduced from 70.1 ⫾ 4.6
mL/day in the usual alcohol period to 19.1 ⫾ 2.5 mL/day
in the reduced alcohol period (P ⬍ .0001). Serum ␥-GTP
was significantly lower in the reduced alcohol period than
in the usual alcohol period (54.2 ⫾ 4.7 U/L v 62.7 ⫾ 6.0
U/L, P ⬍ .01). The subject’s body weight did not differ
significantly between the two periods.
Fig. 1 depicts the 24-h trendgram of BP and heart rate
in each period. Table 1 lists the average values of BP and
heart rate for the entire 24-h period, daytime and nighttime. The 24-h and the daytime systolic BP were significantly lower in the reduced alcohol period than in the
AJH–February 2002–VOL. 15, NO. 2, PART 1
ALCOHOL AND BLOOD PRESSURE AND HEART RATE VARIABILITY
127
Table 1. Ambulatory blood pressure and heart rate
during the usual alcohol and reduced alcohol periods
Usual
Alcohol
Period
Reduced
Alcohol
Period
P
24-h
Systolic BP
(mm Hg)
128.2 ⫾ 1.8 125.0 ⫾ 1.9 ⬍.05
Diastolic BP
(mm Hg)
78.5 ⫾ 1.1
78.2 ⫾ 1.1
NS
Heart Rate
(beats/min)
82.7 ⫾ 1.7
77.4 ⫾ 1.9 ⬍.0001
Daytime
Systolic BP
(mm Hg)
135.8 ⫾ 2.0 132.4 ⫾ 2.1 ⬍.05
Diastolic BP
(mm Hg)
84.8 ⫾ 1.3
83.7 ⫾ 1.2
NS
Heart Rate
(beats/min)
88.1 ⫾ 1.8
83.9 ⫾ 2.1 ⬍.001
Nighttime
Systolic BP
(mm Hg)
112.3 ⫾ 1.9 110.4 ⫾ 1.8
NS
Diastolic BP
(mm Hg)
65.1 ⫾ 1.0
67.2 ⫾ 1.2
.05
Heart Rate
(beats/min)
70.7 ⫾ 1.7
63.6 ⫾ 1.8 ⬍.001
BP ⫽ blood pressure; NS ⫽ not significant.
Values are expressed as means ⫾ SE.
usual alcohol period by 3.2 ⫾ 1.2 mm Hg (P ⬍ .05) and
3.5 ⫾ 1.4 mm Hg (P ⬍ .05), respectively, whereas the
nighttime systolic BP did not differ significantly between
the two periods. The 24-h and the daytime diastolic BP did
not differ significantly between the two periods, whereas
the nighttime diastolic BP was insignificantly lower in the
usual alcohol period than in the reduced alcohol period by
2.1⫾ 1.3 mm Hg (P ⫽ .05). With regard to the heart rate,
not only the daytime heart rate, but also the nighttime heart
rate was significantly lower in the reduced alcohol period
than in the usual alcohol period by 4.1 ⫾ 0.9 beats/min (P
⬍ .001) and by 7.1 ⫾ 1.1 beats/min (P ⬍ .001), respectively. The difference in the 24-h heart rate between the
two periods was 5.2 ⫾ 0.9 beats/min (P ⬍ .0001). The
number of total heart beats during 24 h was 119,030 ⫾
2511 in the usual alcohol period and 111,508 ⫾ 2797 in
the reduced alcohol period (P ⬍ .0001).
Fig. 2 shows the 24-h trendgram of the LF component,
the HF component, and the LF/HF ratio in each period.
Table 2 lists the average values of the pNN50, the LF
component, the HF component, and the LF/HF ratio for
the entire 24-h period, daytime and nighttime. Both the
pNN50 and the HF component were significantly higher in
the reduced alcohol period than in the usual alcohol period
in both the daytime and nighttime, indicating that the
alcohol restriction augmented the parasympathetic nerve
activity throughout a 24-h period in these subjects. The
LF/HF ratio was significantly lower in the reduced period
FIG. 2. The 24-h trendgram of the low-frequency (LF) component,
the high-frequency (HF) component, and the LF/HF ratio during the
usual alcohol (●) and reduced alcohol (䡩) periods. Both the LF and HF
components were significantly higher in the reduced alcohol period
than in the usual alcohol period in both the daytime and nighttime.
The daytime LF/HF ratio was significantly lower in the reduced alcohol period than in the usual alcohol period in both the daytime and
nighttime.
than in the usual period in both the daytime and nighttime
values.
Discussion
A large number of cross-sectional epidemiologic studies
have shown a clear relationship between alcohol consumption, high BP, and the prevalence of hypertension.1,2 Intervention studies have also shown that the cessation of
alcohol drinking reduces office BP in normotensive and
128
ALCOHOL AND BLOOD PRESSURE AND HEART RATE VARIABILITY
6.5
5.02
4.00
1.02
⫾
⫾
⫾
⫾
1.1
0.14
0.15
0.09
4.6
5.01
3.69
1.32
⫾
⫾
⫾
⫾
0.9
7.4 ⫾ 1.2
0.15 5.25 ⫾ 0.15
0.15 4.08 ⫾ 0.17
0.08 1.17 ⫾ 0.09
⬍.05
⬍.01
⬍.001
⬍.01
3-week alcohol restriction significantly increased the indices of parasympathetic nerve activity and decreased the
index of sympathovagal balance throughout a 24-h period
in habitual drinkers, suggesting that the disadvantageous
effects of alcohol intake on autonomic nerve activity continue after its elimination and that the effects are sustained.
In conclusion, 3-week alcohol restriction produced reductions in ambulatory systolic BP, heart rate, and the
index of sympathovagal balance, and augmentations of
parasympathetic indices of heart rate variability in Japanese male drinkers. Restriction of alcohol intake among
moderate-to-heavy drinkers is recommended, specifically
from the point of view of an improvement in the autonomic nervous function.
12.1
5.05
4.67
0.37
⫾
⫾
⫾
⫾
1.8
0.15
0.19
0.11
⬍.001
⬍.001
⬍.001
⬍.001
References
Table 2. Indices of heart rate variability during the
usual alcohol and reduced alcohol periods
Usual
Alcohol
Period
24-h
pNN50 (%)
LF, ln (msec2)
HF, ln (msec2)
ln (LF/HF)
Daytime
pNN50 (%)
LF, ln (msec2)
HF, ln (msec2)
ln (LF/HF)
Nighttime
pNN50 (%)
LF, ln (msec2)
HF, ln (msec2)
ln (LF/HF)
AJH–February 2002–VOL. 15, NO. 2, PART 1
Reduced
Alcohol
Period
11.1
5.32
4.50
0.82
21.4
5.47
5.40
0.07
⫾
⫾
⫾
⫾
⫾
⫾
⫾
⫾
1.5
0.14
0.16
0.10
2.7
0.17
0.18
0.13
P
⬍.0001
⬍.001
⬍.0001
⬍.01
pNN50 ⫽ the percentage of differences between adjacent normal
R-R intervals ⬎50 msec; LF ⫽ low-frequency component; HF ⫽
high-frequency component.
Values are expressed as means ⫾ SE.
hypertensive men.3,4 However, attempts to reproduce
these findings by ambulatory BP monitoring have shown
inconsistent results. Recently, Kawano et al17 reported that
the restriction of alcohol intake for 4 weeks lowered
daytime systolic BP but increased systolic and diastolic
nighttime BP without affecting the average 24-h systolic
and diastolic BP in Japanese men with hypertension. However, Aguilera et al18 reported that 1-month alcohol abstinence in 42 heavy drinkers significantly decreased systolic
and diastolic BP without affecting its circadian pattern. In
the present study, the restriction of alcohol intake for 3
weeks significantly lowered the 24-h and daytime systolic
BP, but slightly increased the nighttime diastolic BP in
Japanese male drinkers. The disparity in these results
including ours may be in part explained by differences in
study protocol and the subject’s baseline characteristics.
Further studies are needed to obtain conclusive information on the chronic effect of alcohol restriction on ambulatory BP in habitual drinkers.
In the present study, more marked effects of alcohol
restriction were observed on heart rate and time and frequency domain measures of heart rate variability. To date,
there have been some reports that acute alcohol intake
significantly changed measures of heart rate variability in
healthy subjects,9,10 patients with coronary heart disease,11
and patients with a history of alcohol-induced atrial fibrillation.12 However, little is known about the chronic effect
of alcohol restriction on heart rate variability in habitual
drinkers. To the best of our knowledge, this is the first
study in which the chronic effects of alcohol restriction on
several measures of heart rate variability were examined
during 24 h by intervention and a randomized trial in the
same individuals. In the present study, we found that
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